The earth's atmosphere is comprised primarily of nitrogen and oxygen. Nitrogen is predominant in that air composition is 78.084% nitrogen by volume and 20.946% oxygen by volume. Thus, nitrogen is extremely plentiful.
Nitrogen becomes a liquid at -320.degree. F. When nitrogen vaporizes, it has a very high cooling capacity (latent heat). Nitrogen and the cryogenic property of nitrogen have been known for over 200 years. Two types of systems are possible using nitrogen. First, it is known to use a closed-coil, heat-exchanger system. The problem with such systems is that there can be a surging effect as liquid nitrogen gassifies. Unless such systems are carefully designed, this can lead to high pressure and the possibility of explosion. Others have worked at solving the problems with closed systems. Acceptable designs, however, become very complex, and are ultimately expensive. Secondly, liquid nitrogen as disclosed in the present application can be used in an open system by releasing the liquid nitrogen to gassify in the space to be air-conditioned. Until the present invention, liquid nitrogen has not been used in an open system for a room air-conditioner as disclosed in the present invention.
In conventional air conditioning and refrigeration systems, compressors are used. Chlorofluorocarbons, such as freon, are used as refrigerants. Such gases are now known to endanger the ozone layer of the earth. Consequently, air conditioning and refrigeration systems must be changed. Furthermore, the use of individual compressors is energy-intensive and expensive. Present air conditioning and refrigeration systems are not environmentally friendly.